The environment around the galaxy M60 contains a very dense galaxy called M60-UCD1.
At first I was kind of surprising this galaxy was even noticed being so close to M60. Turns out a closer look with Chandra shows it to be very distinctive.
The densest galaxy in the nearby universe may have been found. The galaxy, known as M60-UCD1, is located near a massive elliptical galaxy NGC 4649, also called M60, about 54 million light-years from Earth.
This composite image shows M60 and the region around it, where data from NASA’s Chandra X-ray Observatory are pink and data from NASA’s Hubble Space Telescope are red, green and blue. The Chandra image shows hot gas and double stars containing black holes and neutron stars, and the Hubble image reveals stars in M60 and neighboring galaxies including M60-UCD1. The arrow points to M60-UCD1.